1. Field of the Invention
The invention relates to an awning, in particular a sun room awning, comprising a fabric-roll shaft for retracting and extending an awning fabric; wherein the inward end of the awning fabric is joined to the fabric-roll shaft and the outward end of the awning fabric to a drop-out bar, and the drop-out bar is run in lateral guide rails; wherein elastic pull straps act on the drop-out bar on the side opposite the awning fabric, the pull straps being deviated by a deflection pulley in the vicinity of the end of the guide rail, and reversed towards the fabric-roll shaft and wound on the fabric-roll shaft upon extension and unwinding of the awning fabric and exercising tensile stress on the drop-out bar and thus on the awning fabric; wherein unwinding the awning fabric and winding up the pull straps take place by an electric motor drive of the fabric-roll shaft, and switchgear is provided for switching off the drive of the fabric-roll shaft upon complete extension.
2. Background Art
An awning of the generic type is known from U.S. 2003/0019588 A1. The sun room awning there described comprises elastic pull straps for the awning fabric to be tautened even when partially extended. Complete extension of the awning fabric is conventionally detected by a touch sensitive switch or an optical switch, in dependence on which the electric drive is stopped.
It is an object of the invention, in an awning of the type under regard, to ensure reliable tautening of the awning fabric and optically attractive appearance, in particular upon complete extension, accompanied with the fundamental advantages offered by elastic pull straps.
According to the invention, this object is attained by the switchgear acting on the drive of the fabric-roll shaft in such a way that the drive is switched off only after maximum extension being exceeded and the awning fabric being wound up by a defined angular range in the original direction of extension.
Switchgear according to the invention can vary in design. For instance, it can be put into practice in the form of a torque limiter that is available in lots of electric motors; in the form of a force-displacement transmitter that is integrated in the electric motor; in the form of electronic measuring means by which to detect the relative phase position of current and voltage as a function of strain on the electric motor; or in the form of external switchgear.
According to the invention, the conventional limit stop is abandoned and the power of the electric drive is used for tautening the awning fabric; or switching off in dependence on displacement is effected only when maximum extension has been exceeded.
In particular, provision can be made for the motion of the awning fabric to be stopped in dependence on torque upon extension as well as retraction.
Primarily, the idea will be to use an electric motor. However it is conceivable, in particular in the case of window awnings, to provide manual actuation, with the torque sensor, as it were, being replaced by an operator sensing. For maintenance of the set degree of fabric tautening, a self-locking mechanism must be provided between the manual actuating system, in particular a crank, and the fabric-roll shaft.
The awning fabric is fixed by piping in a piping groove of the fabric-roll shaft in a manner known per se.
In keeping with another embodiment, a deflection pulley for each pull strap is provided in front of the fabric-roll shaft in such a way that the pull straps run along the guide rails.
An advantageous possibility of putting into practice the switch-off behaviour according to the invention resides in that the switchgear is released in dependence on the tensile stress on the pull straps and on the awning fabric, in particular by the switchgear comprising a torque transmitter that is disposed on the fabric-roll shaft.
The invention also relates to a method of extension control of the awning fabric of a sun room awning, which is characterized in that the awning fabric, upon maximum extension, is wound up in the original direction of extension until given and desired tautening is reached.
Details of the invention will become apparent from the ensuing description of an exemplary embodiment, taken in conjunction with the drawing.